Epidemiology of the acute respiratory distress syndrome and the prognostic validity of SpO2:FiO2 under the expanded Global definition

The Global consensus definition of acute respiratory distress syndrome (ARDS) broadened the syndrome to include patients on high-flow nasal cannula and hypoxia as defined by the ratio of the saturation of oxygen to fraction of inhaled oxygen (SFR). We sought to compare the incidence and outcomes of ARDS under the 2012 Berlin versus 2023 Global definitions, and to examine the relationship between SFR-derived categories of severity and mortality, in a prospective cohort of critically ill patients with sepsis. Of the 950 included patients, 466 (49%) met criteria for ARDS under the Global definition and 427 (45%) met criteria for ARDS under the Berlin definition during the 6-day follow-up period. Among patients with ARDS, the Global definition allowed for ARDS qualification a median of 3.0 h earlier than the Berlin definition. Mortality was comparable between the Global and Berlin definitions at onset but substantially lower for patients who never went onto meet the Berlin definition. SFR was predictive of 30-day mortality and exhibited moderate correlation with the ratio of partial pressure of oxygen to fraction of inhaled oxygen (PFR). Our work establishes an increased incidence and modestly decreased time to diagnosis of ARDS under the Global definition and supports the prognostic validity of SFR.